Андреевская спектроскопия железосодержащих сверхпроводников: температурная зависимость параметров порядка и их скейлинг с Тc
The unexpected discovery in 2006 of the first layered Fe-based high-temperature superconductor (HTSC), LnOFePn
(where Ln is lanthanide, Pn is pnictide; hereafter referred to as 1111), becomes a key issue in modern solid-state physics. Since 2008, the class of iron-based superconductors has greatly expanded: several families of iron pnictides and chalcogen-
ides have been synthesized. The crystal structure of oxypnictides is reminiscent of that of cuprates and is, in fact,
a stack of superconducting Fe±As layers alternating along the c-direction with spacers, nonsuperconducting oxide blocks,
LnO. In spite of the pronounced layered structure and anisotropic physical properties, the electron subsystem in Fe-
based superconductors is less quasi-two-dimensional than that in cuprate HTSC, because the height of the Fe-As blocks
exceeds the thickness of the CuO2 planes, whereas the distance between superconducting blocks in iron-based superconductors is significantly shorter than that in cuprates. This seems to be a reason why the critical temperature of Fe-based superconductors, though being as high as Tc=57K, still does not reach the cuprate one.